It is typical for thermometers and thermal switches to be calibrated using a drywell. Drywells may include a receiver in which a thermometer or thermal switch is inserted. A heating element and temperature sensor are in thermal contact with the receiver such that the temperature within the receiver may be accurately set. The set temperature of the drywell may then be compared to the readout temperature of the thermometer or the switching temperature of a thermal switch to determine its accuracy. In some uses, a reference thermometer is inserted within the receiver along with the thermometer or switch being calibrated, and the readout of the reference thermometer is used for calibration purposes.
A ventilation system cools the housing in which the receiver is mounted in order to avoid damage to the housing and electronic components of the drywell. The ventilation system typically directs air upward through the drywell in order to avoid excessive heating of a support surface. Often, the vented air heats the probe to the point that it can no longer be comfortably or safely handled by an operator.
Some operators will wrap foil around the probes to reduce heating of the probe. Others will put a set of baffle plates having an opening for the probe on top of the drywell. The plates are expensive to manufacture and complicate set-up and storage of the drywell. In use, the plates may become hot and unsafe for use. Inasmuch as they are not contained within the housing of the drywell, operators risk burns from handling the plates. The plates also interfere with proper venting of the drywell 10. Improper venting causes variation from the calibrated operating condition of the drywell resulting in measurement errors. Improper venting may also damage heat sensitive components.
In view of the foregoing it would be an advancement in the art to provide an improved method for venting a drywell to avoid heating the probe.